1. Field of the Invention
The present invention relates to a corrosive-resistant soft magnetic film formed of a CoFe alloy, which is used, for example, for the core of thin-film magnetic heads, having a saturation magnetic flux density larger than that of NiFe alloys. The present invention also relates to a thin-film magnetic head using the soft magnetic film and further relates to methods of manufacturing the soft magnetic film and the thin-film magnetic head.
2. Description of the Related Art
As the demand for a high recording density has been increasing, a magnetic material having a high saturation magnetic flux density Bs has been required to be used for, for example, the core layer of a thin-film magnetic head so that the magnetic flux is concentrated in the vicinity of the gap in the core to improve the recording density.
NiFe alloys are typically used for a magnetic material. The NiFe alloys are formed by electroplating with direct current and have a saturation magnetic flux density Bs of about 1.8 T.
In order to increase the saturation magnetic flux density of the NiFe alloys, for example, a pulsed current has been used for electroplating instead of using a direct current.
Thus, the saturation magnetic flux density Bs of the NiFe alloys has been improved. However, the Bs is at most 1.9 T and a Bs of 2.0 T or more is rarely achieved.
Increasing the saturation magnetic flux density Bs causes the film surface to become rough, and consequently the NiFe alloys are readily eroded by various solvents used for manufacturing the thin-film magnetic heads.
Alternatively, CoFe alloys are often used for a magnetic material. The Co content of a typical CoFe alloy is about 50 mass %, and such a composition ratio results in a film having a low saturation magnetic flux density Bs and an extremely rough surface, and therefore the film can be eroded.